The invention relates to irrigation valves and more particularly to large capacity valves for controlling water distributed from terminal irrigation channels to agricultural fields. Customarily such valves have been sliding or gate types, since the multiplicity of valves needed in a large field precludes use of conventional cast metal line valves. The distirbution of water from the main or terminal irrigation channel is subject to several variables, including the type of crop to be watered, the season, soil porosity, rainfall and field grade or slope. It is usual for the water to be discharged from the irrigation channel through the channel wall into several spaced water spreading and velocity limiting structures to minimize erosion at the point of water entry to the field.
The number of distribution ports is an optimum arrived at by considering the amount of water desired for the field at a given time in view of the field's absorbsion factors and the volume of flow in the channel, the desirability of having as few primary or terminal channels as possible crossing the fields, the inclination of the agricultural surface and the porosity of the soil. The present invention provides a distribution valve that is not only inexpensive to fabricate, but that is also capable of controlling large volumes of water at high pressures, is capable of diverting the emerging torrent to limit water velocity, and that is capable of either remotely controlled pneumatic operation or in situ manual operation.